Sometimes people at regattas look at me funny because I've never really taken off all the crap that I have to strap to it for the Tybee, but theres a rather sizeable diving knife on there that mounted right on my left chest area that simple click in place, pull down system. I've not had to use it yet, thankfully, but I've practiced cutting lines while holding my breath underwater. Its harder than you think, especially if you're panicing.